Sorting and retrieving items to fill a customer order can be laborious and time consuming. Many large organizations have extensive storage areas in which numerous and diverse items are stored and/or from which they are retrieved. Sorting and retrieving items from the hundreds or thousands of storage areas requires significant labor to perform manually. In many fields, automated picking has developed to reduce labor cost and improve customer service by reducing the time it takes to fill a customer order. However, the known systems of automatically handling the materials are either very expensive or have limitations that hamper their effectiveness. Accordingly, there is a need in a variety of material handling applications for automatically storing and/or retrieving items.
By way of illustrative example, some automated systems utilize a conveying system that includes a plurality of independently operated vehicles. Problems arise in such conveying systems if items being conveyed by the vehicles overhang the edges of the vehicles or extend upwardly above a certain height.
Additionally, automated systems may include a picking station where a worker picks items from the vehicles. If a vehicle moves away from the station while the workers picking an item, damage to the item on injury to the operator may occur. Therefore, it is desirable to prevent a vehicle from advancing away from the picking station while the operator is picking an item.